DESCRIPTION: It has been almost 20 years since the last comprehensive meeting occurred on the Biology of Cilia and Flagella. Since that time, new discoveries in the basic cell and molecular biology of cilia and flagella have led to an increase in not only basic research on these organelles, but clinical research related to the role of cilia and flagella in certain diseases. Much of this interest has been derived from the discovery of the Intraflagellar Transport process in flagella in 1992. The molecular basis of the IFT process, which is required for the assembly and maintenance of virtually all eukaryotic cilia and flagella, has led to the discovery of genes encoding ciliary proteins involved in a variety of human diseases in which, heretofore, the role of cilia was unsuspected. Among these diseases is the most common life-threatening inherited disease of humans, polycystic kidney disease (PKD), which has now been shown to involve the absence or abnormal function of the primary cilia of kidney tubule cells. Another example is Retinitis Pigmentosa; although it has been known for decades that a cilium gives rise to the rod outer segments of the retina, it has only been within the past few years that the transport processes occurring within this connecting cilium have been related to rod outer segment degeneration and blindness. In the 1970s, Bjorn Afzelius implicated aberrant structure of the ciliary dyneins arms in the etiology of Kartagener Syndrome and Situs Inversus (organs misplaced to wrong side of body). However, it has only been in the past few years that the presence and motility of cilia on the nodal cells of vertebrate embryos have been implicated in the basic signaling processes involved in these pathologies. Recent comparative genomic and proteomic analyses of cilia and their associated basal bodies have led to the discovery that cilia and basal bodies are involved in another new set of diseases, including Bardet Biedl Syndrome (BBS) and Congenital Hydrocephalus. The association between male fertility and defective sperm flagella has long been known, but only now are the specific genes responsible for this pathology being identified. Finally, an entire new area of research on cilia concerns their possible role in the cell cycle. Although it has been know for over a decade that the cilia of most G-0/G-1 cells in our body (or in culture) resorb prior to cell division, this has been only a correlation. New results indicate that certain ciliary proteins, including at least one of the IFT proteins, are required for the normal completion of the cell cycle. It was the organizers' desire to have a comprehensive meeting in which those doing research on the basic cell biology of cilia and flagella would meet with the workers concentrating on the role of these organelles in diseases. It is with this goal in mind that we have put together a meeting in which leaders in research on diseases such as PKD, Situs Inversus, Hydrocephalus and male infertility can meet with others researching the biochemistry, structure, and assembly of cilia and flagella. Before attempting to organize this meeting we polled various leaders in the field and found them to be uniformly enthusiastic about the possibility. We have tested preliminary drafts of the sessions on them, and taken their suggestions into consideration in designing the program. (Relevance): The planned meeting will bring together researchers working on the basic cell and molecular biology of clia and flagella with those working on the role of cilia and flagella in diseases such as blindness and polycystiuc kidney disease.. It is a timely meeting because it has only been in the past few years that cilia and flagella have been implicated in the pathology of an increasing number of human diseases. It will be the first and largest meeting with this type of focus ever organized. [unreadable] [unreadable] [unreadable]